It is known that new, clean automotive engines operate more efficiently than older ones that have accrued deposits of carbonized soil in the cylinder areas. They also produce less pollutant gases in the form of tailpipe emissions.
The functional problems of older engines have resulted in the use of more highly refined gasoline/alcohol mixtures, detergent gasolines, computerized fuel injection systems, and in the marketing of engine injector solutions designed to solubilize the offending deposits. The pollution problem has been partly resolved by the use of costly catalytic converter equipment in a few countries. Worsening smog conditions and related air pollution problems in metropolitan areas attest to the fact that these approaches are relatively ineffective.
For many years there has been a search for engine additives that, when injected directly into the upper cylinder areas, would exert a profound cleaning effect and thus serve to remove carbonized varnishes and sludge deposits that form on spark plugs, fuel orifices and cylinder walls. These deposits inhibit the optimum burning of fuel. As such, they reduce mile-per-gallon efficiency. Additionally, they tend to partly plug critical orifices, interfere with spark gap operation of spark plugs, cause piston sticking, and strongly promote the generation of partially burned pyrolysis products during combustion of gasolines and diesel fuels. Some fuel remains unburned. All these products are discharged into the exhaust system. They include unburned hydrocarbons (aliphatics, cyclics and aromatics), polycyclic alcohols, aldehydes and acids (sometimes carcinogenic), oxygenated hydrocarbons of other types, and poisonous carbon monoxide gas. These effluents are, to various degrees, further oxidized by the catalytic converter. But significant amounts escape from the tailpipe and those pose serious environmental hazards to humans, animals and crops. All are included in the Federal Clean Air Act, as amended, for this reason. Environmental Protection Agency regulations under the act have imposed severe limitations on the airborne concentrations of these vapors and particulates which, at this time, at least seventy counties and air management districts cannot comply with unless they would be willing to invite an intolerable degree of economic distress.
Most of the discharged tailpipe vapors are capable of chemically reacting with airborne nitrogen (II) oxide in ways that indirectly cause the formation of excessive levels of tropospheric or ground-level ozone. This gas is a strong irritant and possible proto-carcinogen that is directly implicated in smog formation. The Clean Air Act regulations limit ozone concentrations to 0.12 ppm and carbon monoxide levels to 9.0 ppm in air.
Test methods for determining product efficacy have been developed. They have been used to obtain data on the relative cleaning efficiency of individual chemicals, combinations of two or three chemicals that may show synergistic activity, or on completely formulated concentrates. A well regarded screening method uses the following procedure:
a. Carefully remove a spark plug from an engine. PA0 b. Using an air knife, blow away any loose contamination. (Optional) PA0 c. Weigh the spark plug. PA0 d. Immerse it in the test liquid for five minutes at 77.degree. F. (25.degree. C.). PA0 e. Rinse momentarily in a volatile solvent, such as 1,1,1,-trichloromethane. PA0 f. After or during drying, repeat the air knife removal of loose contamination. (Optional) PA0 g. Reweigh and note weight loss due to contaminant removal. PA0 h. Visually compare with original spark plug condition, to establish approximate per cent of contaminant removal. PA0 i. Using a mild abrasive suspension/dispersion, a bronze buffing wheel or other suitable process, remove any remaining contaminant without removing any of the steel spark plug substance. PA0 j. Determine weight loss due to 100% contaminant removal. PA0 K. Calculate percent removal due to immersion in the test liquid and compare with visual result of step h. PA0 a. Heavy baked-on varnish/sludge deposits. PA0 b. Light, baked-on varnish/sludge deposits. PA0 c. Highly carbonized, baked-on varnish/sludge deposits. PA0 a. Dynamic firing voltages (kV). PA0 b. Specific exhaust gas concentrations (upstream from the catalytic converter) including: i. Unburned hydrocarbon vapors (ppm). ii. Carbon monoxide gas (ppm). iii. Oxygen gas (ppm). iv. Carbon dioxide gas (ppm). PA0 c. Minimum smooth idling speed (rpm). PA0 d. Increase in idling speed due to treatment (rpm). PA0 e. Engine smoothness at idling speed due to treatment. (Substantive) PA0 f. Degree of spark plug cleaning--by observation. PA0 g. Reliability of the CSPIT, as a predictive test method. PA0 a. Select a car whose engine has been driven many thousands of miles on the same set of spark plugs. PA0 b. Remove one or more spark plugs and examine for amount and type of varnish/sludge, after blowing off excess with an air knife. PA0 c. Replace, using same spark plugs, or different test plugs. PA0 d. Snap accelerate the engine to about 2000 rpm and run for two minutes on gasoline. PA0 e. Snap accelerate the engine to about 5000 rpm and run for a few seconds to purge any loose carbonaceous matter out of the cylinders. PA0 f. Conduct control tests. PA0 g. Conduct product tests. PA0 h. Remove the one or more test spark plugs and determine percent sludge removal.
Various modifications of this procedure have been used to determine the efficiency of over a hundred substances and blends, during product development.
In this test it will be appreciated that no two spark plugs will give identical results, even if they were used side by side for the same service life in a given engine. Some deposits will be heavier, others will be more intensely burned on, and some will exhibit higher degrees of pyrolytic carbonization. This has made it necessary to differentiate between spark plugs when testing by what is termed "the Cold Spark Plug Immersion Test" (CSPIT). Three categories have been established:
In the case of well-synergised, highly effective formulas of the subject invention, CSPIT removal has been 90-100% for the light, baked-on varnish/sludge deposits and 50-60% for the other two categories.
A large number of tests have been made on automotive engines. They have been used to determine such attributes as:
Typical tests results are provided in the next section. They show that the CSPIT method is a reliable predictive assay, removing about 90 percent as much spark plug contaminants as are removed in the same time period by what is termed "The Hot Engine Cleaning Test" (HECT).
A well regarded procedure for conducting the HECT assay is recited as follows:
Measure dynamic firing voltage (kV) on all cylinders, at idling rpm. PA1 Measure tailpipe emissions at idling rpm. PA1 Measure kV at low-cruise (1500 rpm). PA1 Measure kV at high-cruise (2500 rpm). PA1 Measure tailpipe emissions at high-cruise (2500 rpm). PA1 Connect product dispenser to engine. PA1 Run engine at 2400-2500 rpm and add product. (Typically, add 260 grams of product in five minutes). PA1 Repeat steps d. and e. PA1 Repeat tests listed under f.
Repeating the CSPIT procedure on cleaned spark plugs results in very little additional contaminant removal; e.g. 5-15% more.
The cleaning ability and emissions reduction properties of the subject composition have been evaluated in comparison with those of several of the ten or twelve other cleaners currently on the market. It is significantly better. Although these products make label claims promising to improve engine performance and prolong the service life of catalytic converters by reducing harmful emissions, in fact they demonstrate very limited benefits. Consequently, the present market is small and rather static. Advertising for the compounds is almost non-existent, and some firms include them only to round out a line of automotive products.
Accordingly, the subject invention offers great advantages over the products currently being marketed, and offers the first effective engine cleaning composition compatible with fluorosilicone automotive gaskets.